Partially Premixed Combustion Arne Andersson Magnus Christensen DEER 2011 Conference High Load Low Temperature Combustion - enabled by introduction of “new” fuels RCCI PPC ´Reactivity Controlled CI´ Partially Premixed Combustion very high ON +very high CN in-between ON/CN i.e. neat ethanol + Diesel i.e. Naphtha or gasoline/diesel IMEP 17 bar w/o EGR reported IMEP 26 bar achieved Low load High load CETANE CETANE OCTANE OCTANE Power density - a prerequisite for downsizing and transport efficiency Volvo Technology Arne Andersson, DEER 2011 PPC use a gasoline type fuel 600 Single injection Prail = 2400bar Prail = 1500bar 500 • BSNOx ~ 0.5g/ Low Cetane 400 ignition delay reduce soot (more premix) 300 increase efficiency (faster heat release) 200 aRoHR [J/CAD] & Pcyl [bar] Low load problems (noise, HC+CO) 100 0 330 340 350 360 370 380 390 400 • High volatility Crank Angle Position [edeg] No wall wetting; Inject anytime! • Low viscosity A lubricity additive needed Volvo Technology Arne Andersson, DEER 2011 CR requirement for ignition HCCI test for PRF blends ignition becomes demanding for ON > 80 CR>17 needed for cold start? Diesel is similar to PRF 30 Port injected PRF0 to PRF100 Volvo Technology Arne Andersson, DEER 2011 Controlling CO and HC at low load uncooled EGR setting: Inlet Manifold Temp raised from 38 to 70 C We must do more at lower loads! Volvo Technology Arne Andersson, DEER 2011 Ways to improve temperature at TDC 50 1200 45 1100 40 1000 35 ε = 15.8 900 30 ε = 17.3 800 25 VVA 50° Pcyl (bar) Pcyl trottle 20 (K) Tcyl 700 hot EGR 15 600 10 500 5 400 0 300 -90 0 90 -90 0 90 CAD CAD Influence on in cylinder temperature at TDC by: increased compression ratio, Miller, intake throttling and hot EGR Hot EGR still the best Volvo Technology Arne Andersson, DEER 2011 Exhaust re-breathing is another way to increase in cylinder temperature 1600 1400 1200 1000 ref 800 T(K) rebreathing 600 400 200 0 -90 0 90 CAD In Cylinder temp with and without re-breathing Re-breathing Volvo Technology Arne Andersson, DEER 2011 PPC test results with single stage turbo boundary conditions A load sweep from IMEP 8 to 21 bar From premixed to diffusion combustion Volvo Technology Arne Andersson, DEER 2011 1200rpm/IMEP8, soot free combustion at very low NOx 1200rpm / IMEP 8 NOx/Soot trade-off Gross Indicated Efficiency 0.10 60 VSD Pinj: 2400bar ON87, build 1 0.08 ON87, build 1 ON87, build 2 55 ON87, build 2 0.06 ON87, build 3 ON87, build 4 50 ON87, build 3 0.04 ON87, build 4 Efficiency [%] Efficiency BSSoot [g/kWh] BSSoot 0.02 45 0.00 40 0.0 0.5 1.0 1.5 2.0 0.0 0.5 1.0 1.5 2.0 BSNOx [g/kWh] BSNOx [g/kWh] Soot free due to premixing Note that diesel is injected at 2400 bar Volvo Technology Arne Andersson, DEER 2011 …COMPARED TO VSD10 1200rpm/IMEP12, significant potential on soot and BSFC with gasoline type fuel 1200rpm / IMEP12 NOx/Soot trade-off Observed BSFC 0.12 VSD10 VSD10 2400bar 2400bar 0.10 ON87 1500bar 225 N 1 220 ON87 0.08 215 1500bar 0.06 210 0.04 205 BSFC [g/kWh] BSFC 200 BSSoot [g/kWh] BSSoot 0.02 195 0.00 0.0 0.5 1.0 1.5 2.0 2.5 0.0 0.5 1.0 1.5 2.0 2.5 BSNOx [g/kWh] BSNOx [g/kWh] One reason for improved BSFC is shorter combustion duration Volvo Technology Arne Andersson, DEER 2011 IMEP12 – Rate of Heat Release example Diesel 2º CAD ignition delay Gasoline 8º CAD ignition delay 600 Single injection VSD10Prail = 2400bar 2400 (VSD10) bar Prail = 1500bar (ON87) 500 ON87 1500 bar BSNOx ~ 0.5g/kWh RoHR tail is identical! 400 The later part of the combustion is mixing controlled 300 Global mixing is still a major design target! 200 aRoHR [J/CAD] & Pcyl [bar] 100 0 330 340 350 360 370 380 390 400 410 420 Crank Angle Position [edeg] Volvo Technology Arne Andersson, DEER 2011 1800rpm /IMEP21 EGR percentage Observed BSFC VSD10 35 VSD10 2000bar 220 ON87 2000bar ON87 1700bar 30 215 1700bar Same EGR [%] 210 25 EGR level 205 20 BSFC [g/kWh] BSFC 200 0.5 1.0 1.5 2.0 2.5 3.0 3.5 BSNOx [g/kWh] 195 1800rpm / 100% NOx/Soot trade-off 0.5 1.0 1.5 2.0 2.5 3.0 3.5 BSNOx [g/kWh] 0.30 VSD10 2000bar 0.25 ON87 1700bar Slightly improved BSFC 0.20 0.15 0.10 BSSoot [g/kWh] BSSoot 0.05 Still almost soot free at 2 g NOx! 0.00 0.5 1.0 1.5 2.0 2.5 3.0 3.5 BSNOx [g/kWh] Volvo Technology Arne Andersson, DEER 2011 C100 SST Sum up of test results With easy to achieve boundary conditions we can: • Run almost soot free at all tested loads • Get biggest BSFC benefits at road load • Get very low NOx at road load Volvo Technology Arne Andersson, DEER 2011 Transport system implications from “new” fuels need to be investigated • Well To Tank analysis, WTT • Availability • Bio content capability • …. Volvo Technology Arne Andersson, DEER 2011 Compression Ignition with Diesel/Gasoline Blends Diesel 35% + Gasoline 65% = PRF 80 (ON) Volvo Technology Arne Andersson, DEER 2011 Well To Tank efficiency GM/Argonne report using GREET (2001, 2005) 79.9% 86.4% Naphtha 8% more Efficient! Volvo Technology Arne Andersson, DEER 2011 Conclusions • Potentially more than 10% lower CO2 foot print with PPC/Naphtha • Significant soot, NOx and efficiency gains from using PPC • Significant engine design changes needed to handle low load Volvo Technology Arne Andersson, DEER 2011 Acknowledgements This material is based upon work supported by – Department of Energy National Energy Technology Lab under Award Number DE-EE0004232 – Department of Energy National Energy Technology Lab under Award Number DE-FC26-07NT43222 This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof. Volvo Technology Arne Andersson, DEER 2011 .